Endovascular recanalization therapy (ERT) has been a standard of care for patients with acute ischemic stroke due to large artery occlusion (LAO) within 6 hours after onset since the five landmark ERT trials up to 2015 demonstrated its clinical benefit. Recently, two randomized clinical trials demonstrated that ERT, even in the late time window up to 16 hours or 24 hours after last known normal time, improved the outcome of patients who had a target mismatch defined as either clinical-core mismatch or perfusion-core mismatch, which prompted the update of national guidelines in several countries. Accordingly, to provide evidence-based and up-to-date recommendations for ERT in patients with acute LAO in Korea, the Clinical Practice Guidelines Committee of the Korean Stroke Society decided to revise the previous Korean Clinical Practice Guidelines of Stroke for ERT. For this update, the members of the writing group were appointed by the Korean Stroke Society and the Korean Society of Interventional Neuroradiology. After thorough reviewing the updated evidence from two recent trials and relevant literature, the writing members revised recommendations, for which formal consensus was achieved by convening an expert panel composed of 45 experts from the participating academic societies. The current guidelines are intended to help healthcare providers, patients, and their caregivers make their well-informed decisions and to improve the quality of care regarding ERT. The ultimate decision for ERT in a particular patient must be made in light of circumstances specific to that patient.